Hydrogen gas is generated by many devices during both use and storage and generally adversely affects the operation of the device. Further, hydrogen gas build-up within sealed devices can cause the devices to distort by expanding or the devices may rupture.
One device wherein unwanted hydrogen gas may be detrimentally generated is an electrochemical cell. Such gas generation may occur during storage, discharge and, in the case of secondary cells, during charge. The reasons for hydrogen gas generation are varied and include corrosion of the various cell components and overcharging. When hydrogen gas evolution cannot be stopped and the gas cannot be vented, its detrimental effects may be negated by absorption thereof.
The prior art has suggested several means for absorbing hydrogen gas evolved in batteries. Kordesch et al., in U.S. Pat. No. 3,261,714 issued July 9, 1966, discloses an auxiliary electrode for such absorption which is porous and treated with a hydrogen ionization catalyst such as platinum, rhodium, palladium and iridium.
Kozawa, in U.S. Pat. No. 3,939,006 issued Feb. 17, 1976, discloses including a discrete body within an electrochemical cell. The body has an outer casing of a hydrogen permeable membrane with the material within the membrane including specific metal oxides and specific catalysts. The catalysts include the same catalysts as disclosed by Kordesch et al., i.e., platinum, palladium and rhodium ("noble metals") and a few highly reactive compounds or alloys of Group VIII metals such as nickel boride and Raney nickel.
Kozawa et al., in U.S. Pat. No. 4,224,384 issued Sept. 23, 1980, disclose a hydrogen gas absorber for an electrochemical cell consisting of silver catalyzed manganese dioxide.
The known means of absorbing hydrogen disclosed in the prior art specifically require noble metal or silver catalysts for their effectiveness. In fact Kozawa specifically notes that MnO.sub.2 alone is ineffective in absorbing hydrogen. Silver and these noble metal catalysts, particularly platinum, are however expensive and greatly increase the cost of any electrochemical cells or other devices in which they may be used. The highly reactive metal compounds and alloys previously used such as nickel boride and Raney nickel are similarly expensive and are also difficult to properly handle and use.